1. Field of the Invention
The present invention relates to an image pick-up device, to a circuit that reads out the amount of light that strikes photoelectrical conversion elements that are arranged in a matrix in a MOS solid-state image pick-up device, and to an associated method of readout therefrom. More particularly, the present invention relates to a MOS solid-state image pick-up device and drive method therefor, which are suitable for use, for example, in such apparatuses as visual sensors and high-speed cameras, which are required to read an amount of light incident to a photoelectrical conversion element at high speed.
2. Description of the Related Art
FIG. 9 is a circuit diagram of a MOS solid-state image pick-up device of the past, and FIG. 10 is a signal timing diagram showing signals for the purpose of reading out amounts of light from photoelectrical conversion elements that are arranged in a matrix in the MOS solid-state image pick-up device that is shown in FIG. 9.
First, referring to FIG. 9, the circuit of a prior art MOS solid-state image pick-up device will be described.
The MOS solid-state image pick-up device 100 shown in FIG. 9 is formed by a matrix arrangement of m rows and n columns of photoelectrical conversion elements 14 (m, n), each of these photoelectrical conversion elements 14 (m, n) being formed by a photoelectrical conversion element 11 (i, j) (i=1, 2, . . . , m and j=1, 2, . . . , n) and a first enhancement-type n-channel MOS transistor 13 (i, j) (i=1, 2, . . . , m and j=1, 2, . . . , n) for the purpose of vertical switching, and the sources of which is connected to each of these photoelectrical conversion elements 11 (i, j).
The m rows and n columns of conversion elements 14 (m, n) form the photoelectrical conversion element array 10.
Each of the gate terminals of the first vertical switching MOS transistors 13 (i, j) is commonly connected to a first signal line 15 (i) (i=1, 2, . . . , m), which is a vertical gate line 15 (i), for each one of rows, and each of the first vertical signal lines 15 (i) is connected to a vertical shift register 17, this being the vertical scanning circuit 17.
The drain terminals of each of the first enhancement-type n-channel MOS transistors 13 (i, j) used for vertical switching, are commonly connected to each other by a second signal line 19 (j) (j=1, 2, . . . , n), which is a vertical signal line 19 (i), for each one of columns.
Further, each of the second signal lines 19 (j), which are vertical signal lines 19 (j), is connected to a source of a second enhancement-type n-channel MOS transistor 21 (j) j=1, 2, . . . , n) used for horizontal switching, each of the drain of all these second MOS transistors 21 (j) used for horizontal switching, being commonly connected to a third signal line 23, which is the horizontal signal output line.
The gate terminals of each of the horizontal switching second MOS transistors 21 (j) are connected to a horizontal shift register circuit 27, which is a horizontal scanning circuit, via fourth connection lines 25 (j) (j=1, 2, . . . , n), which are horizontal gate lines. The third signal line 23, which is the horizontal signal output line, is connected to the input of a signal amplifier 29 and to one end of a readout load resistance 31, the other end of the readout load resistance 31 being connected to a power supply 33 that provides a constant voltage VM. The output of the signal amplifier 29 is connected to an output signal line 35.
Next, the operation of reading out an amount of light from a MOS solid-state image pick-up device is described below, with reference being made to FIG. 9.
First, the potential of the points of connection between each of the photoelectrical conversion elements 11 (i, j) before reading out the amount of light incident to the MOS solid-state image pick-up device and the sources of each of the MOS transistors 13 (i, j) are set to the constant voltage VM.
In this condition, when light is shined onto the image pick-up device, a photoelectric current that is proportional to the amount of light at each of the photoelectrical conversion elements 11 (i, j) is generated, resulting in the source potential of each of the first MOS transistors 13 (i, j) being reduced to below the constant voltage VM by an amount that is proportional to the amount of light.
Next, the vertical shift register circuit 17, which acts as the vertical scanning circuit, applies a position voltage only to the first signal line 15 (i) for which i=1 of the first signal lines 15 (1) to 15 (m), which are vertical gate lines, which results in n first MOS transistors 13 (1, 1) through 13 (1, n) being turned on, so as to conduct, this resulting in the source potentials of these n first MOS transistors 13 (1, 1) through 13 (1, n) appearing at the second signal lines 19 (1) through 19 (n), these being the n vertical signal lines.
Next, the horizontal shift register circuit 27, which acts as a horizontal scanning circuit, applies a positive voltage pulse sequentially to the fourth connection lines 25 (1) through 25 (n), these being the n horizontal gate lines, this resulting in the n horizontal switching second MOS transistors 21 (1) through 21 (n) being sequentially switched from on to off, so that the source potentials of the n vertical switching first MOS transistors 13 (1, 1) through 13 (1, n) sequentially appear at the third signal line 23, which serves as the horizontal signal output line, from the second signal lines 19 (1) through 19 (n), which act as vertical signal lines, via the second MOS transistors 21 (1) through 21 (n).
When this happens, because the third signal line 23 is, via the readout load resistance 31, connected to the constant-voltage VM power supply 33, a current flows into the third signal line 23 that is proportional to a voltage that has been lowered because of the incident light.
This current is converted to a voltage by the readout load resistance 31, is amplified by the signal amplifier 29 that is connected to the third signal line 23, and is output to the output signal line 35. In this manner, it is possible to know the amount of light that is shined on each of the photoelectrical conversion elements 11 (1, 1) through 11 (1, n) as a voltage value.
Next, the vertical shift register circuit 17 applies a positive voltage to only one of the first signal line, for which i=2, selected from the first signal lines 15 (1) through 15 (n), thereby causing the n vertical switching first MOS transistors 13 (2, 1) through 13 (2, n) to conduct, and the above-noted procedure is repeated so as to enable the determination of the amount of light shining on the n photoelectrical conversion elements 11 (2, 1) through 11 (2, n).
Thus, by sequentially outputting m positive voltage pulses from the vertical shift register circuit 17 to the first signal line 15 (i), and by having the horizontal shift register 27 sequentially output n positive voltage pulses during the time period in which the above-noted pulses are positive, it is possible to determine the amount of light shining on all of the photoelectrical conversion elements 11 (1,1) through (m, n).
FIG. 10 is a drawing that illustrates the operational timing of reading out the amount of light shining on the above-noted photoelectrical conversion elements 11 (1, 1) through (1, n).
The above operation will be described using FIG. 10. A positive potential pulse having a pulse width Tv 37 from the vertical shift register circuit 17 is output to the first signal line 15 (1), which is the vertical gate line.
Pulses having the pulse width Th 39, which change from low level to high level and then from high level to low level with a period of Wh 40, during the period of Tv 37 in which the first signal line 15 (1) is at the high level, are sequentially output to the fourth signal lines 25 (1) through 25 (n), from the horizontal shift register 27, which is the horizontal scanning circuit.
After an elapsed time of Ta 41 after each of the fourth signal lines 25 (1) through 25 (n), which are the horizontal gate lines, changes to a high level, a voltage that is proportional to the current that flows into each of the photoelectrical conversion elements 11 (1, 1) through 11 (1, n) appears at the third signal line 23, which is the input of the signal amplifier 29. This then is output to the output signal line 35 of the signal amplifier 29, so that the amount of light shining on the photoelectric conversion elements is read out.
An MOS solid-state image pick-up device of the past was configured as described above, so as to read out the amount of light shined on the photoelectric conversion elements and, by sequentially turning the vertical switching second MOS transistors 21 (i) on and also having the horizontal switching second MOS transistors 21 (i) turn on in sequence, a current that is proportional to the amount of light shined on the photoelectrical conversion elements 11 (i, j) is sequentially connected to and converted to a voltage by the readout load resistance 31.
That is, if the speed of readout by voltage conversion of a current that is proportional to the amount of light at a single photoelectrical conversion element 11 (i, j) is Ta 41, the time for voltage conversion and readout of the currents that are proportional to amounts of light shined on all the photoelectrical conversion elements 11 (1, 1) through 11 (n, m) would be Ta 41 times n (i.e., Ta 41xc3x97n)
That is, the readout time required for the amount of light shined on all the photoelectrical conversion elements 11 (1, 1) through 11 (n, m) of a MOS solid-state image pick-up device would be (Ta 41xc3x97n)xc3x97m or greater.
Because the setting must be made so that Ta 41 less than Th 39, the readout of the amount of light shined on all the photoelectric conversion elements 11 (1, 1) through 11 (n, m) is at least (Th 39xc3x97n)xc3x97m.
Because the on resistance of the vertical switching first MOS transistor 13 (i, j) is high, the time Ta 41 becomes long, and for this reason there is the problem of an extremely long time required to read out the amounts of light shining on all the photoelectrical conversion elements 11 (1, 1) through 11 (n, m) of the MOS solid-state image pick-up device.
Accordingly, it is an object of the present invention to improve on the drawbacks of the prior art as described above, and in particular to provide a solid-state image pick-up device, and more particularly a MOS solid-state image pick-up device that is capable of reading out the amounts of light shining on all the photoelectrical conversion elements of the MOS solid-state image pick-up device, doing this at high speed and also with good accuracy. An additional object of the present invention is to provide a method of driving a solid-state image pick-up device, this drive method being capable of reading out the amounts of light shining on all the photoelectrical conversion elements of the MOS solid-state image pick-up device, doing this at high speed and also with good accuracy.
In order to achieve the above-noted object, the present invention has the following described basic technical constitution.
Specifically, a first aspect of a solid-state image pick-up device according to the present invention is a solid-state image pick-up device that is formed by a first group of signal lines, a second group of signal lines, each of which intersecting those of the first group of signal lines in a matrix arrangement, a first selection circuit that sequentially selects and drive the first group of signal lines, a second selection circuit that sequentially selects and drive the second group of signal lines, a plurality of photoelectrical conversion element cells that are provided in the vicinity of each one of a region of intersection points formed between each one of lines of the first group of signal lines and each one of lines of the second group of signal lines, and that are connected thereto, and at least an output means for separately outputting individual amounts of received light information of the photoelectrical conversion element cells, and wherein the device further comprising, a multiple signal line received light amount value storage means which is provided separately between either the first group or the second group of signal lines and a prescribed selection circuit which drives the selected group of signal lines and which is provided on each one of the signal lines in the selected group of signal lines, and which individually stores therein, an amount of received light information of each one of a plurality of photoelectrical conversion element cells, each connected to a selected one of the separate signal lines contained in another group of signal lines, respectively, while each of the plurality of multiple signal line received light amount value storage means is further provided with an amount of received light detection means, each of which reads out, respectively, for each one of the signal lines in the another group of signal lines, the amounts of received light information of each one of the plurality of photoelectrical conversion element cells connected to a selected one of the separate signal lines contained in the another group of signal lines, and a switching means that causes the detected amount of received light information to be transmitted to the output means.
A second aspect of a solid-state image pick-up device according to the present invention is a solid-state image pick-up device that is formed by a first group of signal lines, a second group of signal lines, each of which intersecting those of the first group of signal lines in a matrix arrangement, a first selection circuit that sequentially selects and drive the first group of signal lines, a second selection circuit that sequentially selects and drive the second group of signal lines, a plurality of photoelectrical conversion element cells that are provided in the vicinity of each one of a region of intersection points formed between each one of lines of the first group of signal lines and each one of lines of the second group of signal lines, and that are connected thereto, at least an output means for separately outputting individual amounts of received light information of the photoelectrical conversion element cells, a multiple signal line received light amount value storage means which is provided separately between either the first group or the second group of signal lines and a prescribed selection circuit which drives the selected group of signal lines and which is provided on each one of the signal lines in the selected group of signal lines, and which individually stores therein, an amount of received light information of each one of a plurality of photoelectrical conversion element cells, each connected to a selected one of the separate signal lines contained in another group of signal lines, respectively, while each of the plurality of multiple signal line received light amount value storage means is further provided with an amount of received light detection means, each of which reads out, respectively, for each one of the signal lines in the another group of signal lines, the amounts of received light information of each one of the plurality of photoelectrical conversion element cells connected to a selected one of the separate signal lines contained in the another group of signal lines, and a switching means that causes the detected amount of received light information to be transmitted to the output means, wherein, the image pick-up device being configured so that, by selecting a part of signal lines of either one of the first or the second group of signal lines, individual amount of received light information for each of the plurality of photoelectrical conversion element cells, each connected to each one of the signal lines of the selected group of signal lines, is read out, while by sequentially scanning each one of the signal lines in the another group of signal lines, the individual amount of received light information read out from each one of the read photoelectrical conversion element cells is sequentially and separately output to the output means, respectively, wherein in the device, during a period of time in which one of the signal lines of the selected group of signal lines is selected and individual amount of received light information for each one of the plurality of photoelectrical conversion element cells each connected to one of the selected signal line of the selected group of signal lines is output to the output means, by selecting a separate signal line of the selected group of signal lines, individual amount of received light information for a plurality of photoelectrical conversion element cells each connected to the separate signal line of the selected group of signal lines is read out.
A third aspect of an image pick-up device according to the present invention is an image pick-up device having a first group of signal lines, a second group of signal lines, each of which intersecting those of the first group of signal lines in a matrix arrangement, a first selection circuit that sequentially selects and drive the first group of signal lines, a second selection circuit that sequentially selects and drive the second group of signal lines, a plurality of photoelectrical conversion element cells that are provided in the vicinity of each one of a region of intersection points formed between each one of lines of the first group of signal lines and each one of lines of the second group of signal lines, and that are connected thereto, at least an output means for separately outputting individual amounts of received light information of the photoelectrical conversion element cells, a multiple signal line received light amount value storage means which is provided separately between either the first group or the second group of signal lines and a prescribed selection circuit which drives the selected group of signal lines and which is provided on each one of the signal lines in the selected group of signal lines, and which individually stores therein, an amount of received light information of each one of a plurality of photoelectrical conversion element cells, each connected to a selected one of the separate signal lines contained in another group of signal lines, respectively, while each of the plurality of multiple signal line received light amount value storage means is further provided with an amount of received light detection means, each of which reads out, respectively, for each one of the signal lines in the another group of signal lines, the amounts of received light information of each one of the plurality of photoelectrical conversion element cells connected to a selected one of the separate signal lines contained in the another group of signal lines, and a switching means that causes the detected amount of received light information to be transmitted to the output means, wherein, the image pick-up device being configured so that, a plurality of the output means being parallely provided to form a multi-step like configuration, and the device being further configured so that, after a signal line of the selected group of signal lines is selected therefrom, and individual amount of received light information for a plurality of photoelectrical conversion element cells connected to one of the selected signal lines are read out therefrom, respectively, and stored in each one of prescribed storage means, respectively, by selecting a separate signal line of the selected group of signal lines, separate individual amount of received light information for a plurality of the photoelectrical conversion element cells connected to the separate signal line of the selected group of signal lines are read out therefrom, respectively, and stored in each one of prescribed storage means, respectively, and further wherein, the individual amount of received light information for the plurality of photoelectrical conversion element cells connected to the one signal line of the selected group of signal lines and the separate individual amount of received light information for the plurality of photoelectrical conversion element cells connected to the separate signal line of the selected group of signal lines being simultaneously and separately output to each of the plurality of output means, respectively.
A fourth aspect of the present invention is a drive method for an image pick-up device that has, for example, a first group of signal lines, a second group of signal lines, each of which intersecting those of the first group of signal lines in a matrix arrangement, a first selection circuit that sequentially selects and drive the first group of signal lines, a second selection circuit that sequentially selects and drive the second group of signal lines, a plurality of photoelectrical conversion element cells that are provided in the vicinity of each one of a region of intersection points formed between each one of lines of the first group of signal lines and each one of lines of the second group of signal lines, and that are connected thereto, and at least an output means for separately outputting individual amounts of received light information of the photoelectrical conversion element cells, wherein the method of drive is configured so that by scanning either the first group of signal lines or the second group of signal lines, as a selected group of signal lines, an operation of separately reading out the individual amount of received light information for the plurality of photoelectrical conversion element cells connected to selected one of the signal lines of the another group of signal lines, and further operation of outputting the results of the readout to the output means,are performed, sequentially, the method thereof being characterized in that, during one period of time in which each one of the signal lines in the selected group of signal lines are scanned, an operation of reading out the individual amount of received light information for the plurality of photoelectrical conversion element cells connected to each one of at least two selected signal lines of the another group of signal lines group, respectively, and an operation of outputting the information are performed simultaneously or both of the reading out operation and the outputting operation are performed consecutively.
By adopting the above-described technical constitution, an image pick-up device according to the present invention can be contrasted to an image pick-up device from the prior art as follows.
In the case of the prior art image pick-up device, illustrated, for example, as the MOS solid-state image pick-up device 100 of FIG. 9, one of the first signal lines 15 (i), which are vertical gate lines, is selected and the individual amounts of received light information for the plurality of photoelectrical conversion element cells 14 (i, 1) to 14 (i, n) that are connected to the selected first signal line 15 (i) are separately read out, but it was not possible, before the operation of outputting the results of this readout to the output means is completed, to select the next first signal line 15 (i+1), separately read out the individual amounts of received light information for the plurality of photoelectrical conversion element cells 14 (i+1, 1) to 14 (i+1, n) that are connected thereto and output the results of this readout to the output means.
In contrast to this, in the present invention, for example, one of the first signal lines 15 (i), which are vertical gate lines, is selected, and the respective amount of received light information for each of the photoelectrical conversion element cells 14 (i,1) to 14 (i, n) that is connected to the selected first signal line 15 (i) is separately read out and output to the output means and, during the period of performing this operation, it is possible to select the next first signal line 15 (i+1) and to simultaneously perform the operation of reading out the respective amount of received light information of the plurality of photoelectrical conversion element cells 14 (i+1. 1) to 14 (i+1, n) that is connected thereto or the operation of outputting the readout results.
Because, in the manner described above, it is also possible to perform the operation of simultaneously reading out the amount of received light information for the plurality of photoelectrical conversion element cells 14 corresponding to the first signal lines 15 (i) and 15 (i+1), which are adjacent to one another, it is possible to greatly reduce amount of time required to detect and output the amount of received light information for this plurality of photoelectrical conversion element cells.